Surgery-first and Orthodontic-first approaches produce similar patterns of condylar displacement and remodeling in patients with skeletal class III malocclusion

Publication date: Available online 13 February 2019

Source: Journal of Oral and Maxillofacial Surgery

Author(s): Xiaotong He, Jiayi He, Hua Yuan, Wenjing Chen, Hongbing Jiang, Jie Cheng

Abstract

Purpose

s: Condylar displacement and remodeling are critically involved in occlusal and skeletal stability after orthognathic surgery. The aim of the present study was to characterize condylar displacement and surface remodeling after bimaxillary orthognathic surgery in adult patients with skeletal Class III malocclusion treated by surgery-first approach (SFA) or orthodontic-first approach (OFA).

Methods

This retrospective cohort study recruited adult patients with mandibular hyperplasia treated with SFA or OFA. Simultaneous Le Fort I osteotomy for maxillary advancement and bilateral sagittal split ramus osteotomy for mandibular setback were performed in all patients. Original CBCT data before surgery (T0), immediate after surgery (T1) and 12 months postoperatively (T2) were collected and reconstructed for 3-dimensional (3D) quantitative analyses. 3D condylar displacement and remodeling after SFA and OFA were characterized and statistically compared via Mann-Whitney U test and Chi-square test. The significance level was set at P < 0.05.

Results

Twenty-four patients (male/female=1:2; mean age 21.2 years) and 20 patients (male/female=1:1; mean age 23.1 years) were enrolled in OFA and SFA group, respectively. Condylar inferolateral displacement with inward and anterior rotation from T0 to T1 and return movements from T1 to T2 were observed regardless of treatment approach. Significantly greater amount of 3D bodily shift immediately after surgery (2.04 ±1.05 mm in SFA vs 1.22 ± 0.66 mm in OFA; P <0.05) and downward movement 1 year after surgery was observed in SFA compared to OFA. Bone resorption in condylar surface was prevalent and predominantly in its lateral areas, whereas bone formation was frequently observed in anteromedial area in both SFA (45%) and OFA (42.9%).

Conclusions

Similar patterns of 3D condylar displacement and surface remodeling were observed in patients treated with either SFA or OFA.

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